1. Field of the Invention
The present invention relates generally to catheters and more particularly, to a catheter having at least one lumen with an expandable flow area and a method for catheterizing a patient.
2. Background of the Invention
Catheters for the introduction or removal of fluids may be positioned in various venous locations and cavities throughout the body of a patient for introduction of fluids to the body or removal of fluids from the body. Such catheterizations may be performed using a catheter with either a single lumen or multiple lumens. Examples of such catheters are central venous catheters which are typically used for medical procedures such as blood pressure monitoring, blood sampling and the administration of drugs and fluids to a patient. These procedures often require that the catheter have a sufficiently sized lumen or lumens for administering fluids to the patient or withdrawal therefrom.
Generally, a central venous catheter is surgically inserted into a vein, such as the basilica, cephalic, subclavian, or jugular, with the distal tip of the catheter residing in the superior vena cava. These catheters are typically introduced using percutaneous entry techniques, such as the well-known Seldinger technique. In the Seldinger technique, the physician makes an oblique entry into the vein with a beveled needle. A wire guide is then inserted through the bore of the needle about 5 to 10 centimeters into the vein. The needle is thereafter withdrawn, leaving the wire guide in place. The catheter is then inserted over the wire guide, and advanced through the skin at the needle puncture site and into the vein. The Seldinger technique can be modified to include a peelable introducer which can be used to dilate the body vessel. In particular, the introducer sheath can be placed over the wire guide, and after removal of a dilator, the catheter can be placed through the sheath for insertion into the patient. In either of these procedures, the catheter is preferably sized such that the outer diameter (e.g. relatively small outer diameter) facilitates introduction of the catheter through the skin and into the vein. Once the catheter is in place within the vein, the wire guide is withdrawn and therapeutic treatment using the catheter can begin. Preferably, the catheter has sufficient flow area (e.g. catheter lumen with a relatively large flow area) for administering therapeutic treatment to the patient, such as for example, treating the patient with relatively large volumes of fluid during infusion therapy with a central venous catheter. When the therapeutic treatment is completed, the catheter is withdrawn from the patient. Preferably, the catheter is configured with an outer diameter (e.g. relatively small outer diameter) to facilitate being withdrawn from the patient. Currently available catheters with relatively large inner diameter lumens and currently available catheters with relatively small outer diameter shafts result in two diametrically opposed catheter constructions. That is, catheters with relatively large inner diameter lumens have corresponding relatively large outer diameter shafts and catheters with relatively small outer diameter shafts have corresponding relatively small inner diameter lumens.
Accordingly, it may be desirable to have a catheter with a relatively large flow area lumen for therapeutic treatment of a patient while having a relative small outer diameter for facilitating insertion into and/or withdrawal from the patient.